The present invention relates to machinery and methods for exploring beneath the earth""s surface and, more particularly, to stratigraphic exploration.
One conventional technology useful for exploring the subsurface characteristics at a geological location includes the use of a cone penetrometer. This apparatus has a cone with an electronic stress sensor that is forced downward through the various subsurface layers. As the cone penetrates different strata, the data sensed by the cone is either collected in the cone or transmitted back to the surface. This data indicates characteristics and thickness of the different strata below the surface.
Recently, other technologies that fall into the general class known as xe2x80x9cdirect pushxe2x80x9d equipment have been developed to provide other data about subsurface conditions. One common technology of this nature is known as GeoProbe(copyright) and another is HydroPunch.
In practice, these direct push technologies, including the cone penetrometer, are delivered to a field site on some type of mobile platform such as a truck or track-mounted vehicle. The platform is relatively large and heavy in order to handle the forces applied, and support the equipment, involved in direct push techniques. A sensor, such as a cone, is attached to a section of pipe which is, itself, coupled using any of a variety of known means to a mounting system. Included in any of these different platforms are hydraulic rams that attach to this mounting system and produce the downward force needed to push a sensor (and attached piping) down through the ground.
The rams force the mounting system downward which forces the piping and sensor downward as well. As more piping is needed, the mounting system is detached from the top piping section, a new pipe segment is added, and pushing continues. For example, in cone penetrometry, each pipe segment is typically one meter long.
Even though direct push systems can generate up to 40,000 lbs of force, these systems are unable to penetrate or push sensors through consolidated or cemented layers below the surface. In the past, when a consolidated layer was reached, either the site data collection stopped or a conventional drilling rig was brought in to penetrate the consolidated layer.
However, the logistical difficulty in utilizing a conventional drilling rig makes this solution very problematic. An available rig has to first be found and then be delivered to the site. In preparation for the arrival of the drilling rig, the direct push equipment must be cleared from the site and the site prepared for the rig. Water collection ponds and other infrastructure is needed for the conventional drilling rig. Once the drilling operation is completed, the site must be cleaned-up and restored for the return of the direct push equipment.
Accordingly, there is an unmet need for methods and machinery useful with direct push equipment that allows drilling through consolidated surfaces that can be accomplished quickly, efficiently, economically and with as little disruption as possible at a field site.
The present invention addresses these and other needs by providing an air drilling swivel that works with any direct push equipment so as to provide drilling capabilities in the field without the presence of a conventional drilling rig. As a result, the use of direct push equipment is not significantly hampered when consolidated or cemented layers are encountered during subsurface exploration. Within the present application, the term xe2x80x9cdirect pushxe2x80x9d is used for convenience and is intended to encompass both conventional direct push equipment as well as driven, hammer driven, or driven-vibrating equipment.
One aspect of the present invention relates to a method for drilling. According to this aspect direct push equipment is used to push a first set of pipe sections and sensor down a bore hole. Then, the first set of pipe sections and sensor are removed from the bore hole and the direct push equipment. Next a power swivel is attached to the direct push equipment, along with a second set of pipe sections and drill bit; and then drilling is performed further down the bore hole with the power swivel.
Another aspect of the present invention relates to a power swivel for drilling down a bore hole. According to this aspect, the power swivel includes a stationary housing configured to be mounted to direct push equipment; a hollow rotating drive shaft configured to rotate within the stationary housing; and a set of hollow pipe sections. A far end of the pipe sections has a drill bit and a near end of the pipe sections is coupled with the rotating drive shaft such that the hollow region of each pipe section aligns with the hollow region of the rotating drive shaft. Within this arrangement, the stationary housing includes one or more air inlet apertures, and the rotating drive shaft includes one or more air openings and arranged within the housing. These different air openings are arranged so that, while the drive shaft is rotating, the one or more air openings periodically align with the one or more air inlet passages to provide a passage way for air into the hollow drive shaft.
Still other objects and advantages of the present invention will become readily apparent from the following detailed description, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.